Just bought 1.5 blasters in lots of pieces..

[Lindso]

..Yeah so It's project time again. I'm starting with the motor, not doing anything fancy, but runnin into a little hitch with the cylinder;

The cylinder needs to be bored out some, so I took it to get measured, and it's at 72.2mm! Now, I know the big bore kits are somewhere around this size, but I can't tell if it's actually a big bore cylinder, or a stock one that's WAY too big for safety..is that a possibility? I read through searching that 68.25mm is .090 over 90 over is max, so by those means, it couldn't be a stock cylinder, could it? How can I tell if I can safely do this?

 

[UncagedShadow]

Has to be a big bore if there is a sleeve left and it measured that big. Just in case post some pictures of the jug, inside and out...

 

[Lindso]

Okay I only have a couple real close pics available of the inside of the jug that highlight the cylinder scoring more than anything. If they don't help, I can post more a bit later after work;

 

[sicivicdude]

That's a Vito's big bore kit. Congraulations!

Unfortunately, 72.2mm is neither "stock" big bore size or even the next bore size up. It's somewhere in between.

At one time, wossner was making big bore pistons in a 72.25mm. That piston is easily distinguishable by a single intake window in the back of the piston instead of duals like the stock (and vito's pistons).

If the piston is 72mm and the cylinder is actually 72.2mm, you will need to overbore to 72.50mm. Right now, the only big bore pistons available are the cast vito's 72mm, 72.5mm and 73mm.

 

[Lindso]

How can you tell?

And does Wiseco not make a piston this size? I haven't done any business with Vito's in the past but I can't imagine their quality would be low..

 

[yames]

i have the vitos 73mm. i love it but some people dont.

 

[sicivicdude]

Triple exhaust ports and the tiny boost port. It's definitely a vito's cylinder.

Wiseco does not make a piston that size. They USED to make a forged piston (manufactured by wiseco but marketed by vito's) but they have since ran out of them and are waiting for the economy to pick back up before ordering more.

The cast piston will work fine as long as the clearance is proper and you keep an eye on it.

 

[jlsparky7]

Could he sleeve it?

 

[sicivicdude]

There's no need, have it bored to 72.50mm and purchase the cast piston. It'll rock on!

 

[Lindso]

Thanks a lot man. This is the first time I've posted on here in quite some time. Do people make build threads? Or is a 4wheeler build not really a big deal these days? lol

 

[Lindso]

Oh and uh... is this more or less what I'm lookin for?

YAMAHA BLASTER 72.5MM BIG BORE PISTON | eBay

 

[sicivicdude]

People make build threads and they post them in the build thread section.

That piston is exactly what you're looking for.

 

[Larry's Shee]

I was just at Vito's yesturday and they are in the process of moving, so there might be a little extra time in shipping it out. Took ten minutes to find idle screws I needed, lol.

 

[sicivicdude]

Are they moving to a larger shop? Or just someplace different?

 

[theblasterboy]

Do people make build threads ? Omg man do we ever welcome to the sickness by the way. And when you get it back together hold on tight that beoutch will rock your world lol

 

[Larry's Shee]

Moving north of current location, don't know size wise. Don't know if they're even going to have walk-in/ storefront service. Just know rent will be considerably less. Econimy in general and especially in Mich is tough. Well established Yammy dealer closed up back in Jan.

 

[Lindso]

Thanks guys. I got a couple more questions but I'll wait til I have pics. No reason to muck up the engine section with a bunch of pointless questions.

 

[theblasterboy]

Thanks guys. I got a couple more questions but I'll wait til I have pics. No reason to muck up the engine section with a bunch of pointless questions.

Dude go ahead and ask that is what were here for. Just edit pics in later

 

[Lindso]

It's still regarding the cylinder and head, and the crank and will be easier with pics. In the mean time, does anyone have a pic of their stock crank and rod? In or out of the case, it doesn't matter. I'm still trying to figure out what exactly I have in my possession.

 

[sicivicdude]

You CAN identify a stroker crank by looking at it but ONLY by looking at the end of it (from either the primary drive gear or stator side end). Obviously this requires having it out of the cases because the cases block this view normally.

A stock stroke crank has the rod pin hole made just inside of a shiny bossed ring that goes all the way around the edge of the crank. The vito's +3 stroker has the pin just inside of that ring (just slightly farther towards the outside). The hotrods +4 crank has the pin well into the outside ring (noticeably farther because the ring is thicker too).

Other than visual identification, you would have to measure the stroke of the crankshaft during a full revolution. Install the wrist pin and wrist pin bearing with the wrist pin hanging farther out one end. Use a dial (or digital) caliper to measure the distance between the cylinder mating surface at TDC (top dead center) and BDC (bottom dead center). Stock stroke is 57mm. +3 is 60mm and obviously, +4 is 61mm...